# Math Help - Logarithms

1. ## Logarithms

How do you do

Log base 5 of (x ^2 + x + 4) = 2?

2. Originally Posted by Alan306090
How do you do

Log base 5 of (x ^2 + x + 4) = 2?
first, change it to an exponential equation ... you'll get a quadratic to solve.

don't forget to check your solutions in the original log equation for domain issues.

3. Originally Posted by skeeter
first, change it to an exponential equation ... you'll get a quadratic to solve.

don't forget to check your solutions in the original log equation for domain issues.
25 = x ^2 + x + 4

0 = x^2 +x -21

then what? I can't factor it

4. Originally Posted by Alan306090
25 = x ^2 + x + 4

0 = x^2 +x -21

then what? I can't factor it
$x = \frac{-b\pm\sqrt{1^2-4\times 1\times -21}}{2\times 1}=\dots$